CHANGE OF ZINC DISTRIBUTION IN RAT-BRAIN WITH INCREASING AGE

Zinc (Zn) accumulation in the brain of rats of various ages was studie d to look into the significance of Zn for the development and function of the brain. The Zn concentration of the cerebral hemisphere was rel atively low in 1- to 11-day-old rats. The Zn concentration of the cere bellum gradually increased after birth and reached nearly a plateau at 11 days old. At 48 weeks old, the Zn concentrations of the cerebral c ortex and hippocampus formation were approximately twice that of the c erebral hemisphere at the early stage after birth and significantly hi gher than that of the cerebellum. When (ZnCl2)-Zn-65 was injected into two groups of rats at 5 days and 48 weeks old for comparison, Zn-65 d istribution in the brain of the former group was higher than that of t he latter. In the neonatal rats, the highest concentration of Zn-65 wa s found in the cerebellum, followed by the hippocampus formation, a Zn -containing neuron-rich region. In the adult rats, the highest concent ration of Zn-65 was found in the CA3 and dentate gyrus of the hippocam pus formation. At 48 weeks, Zn-65 distribution in the cerebellum was r elatively low and at about the same level as in the cerebral cortex. T hese results suggest that Zn is highly demanded by the cerebellum, whi ch develops rapidly after birth. The increase in Zn concentration with increasing age may reflect the Zn requirement for functioning as an n euromodulator as well as for brain development. (C) 1997 Elsevier Scie nce B.V.